Software keyboards are used to display a keyboard arrangement on a screen of an LCD (Liquid Crystal Display) panel having touch panel functions and enable input of characters on behalf of a mechanical keyboard by using a coordinates detection function of the touch panel.
Unlike common hardware keyboards that involve strokes in the up-and-down (pressing) direction, software keyboards rely only on display on a flat screen, wherein boundaries among adjacent keys cannot be recognized by mechanical projections and depressions. Thus, incorrect inputs frequently occur especially on adjacent keys.
Methods for preventing or reducing such incorrect inputs have been proposed, such as the method of Japanese Patent Laid-Open No. 11-53093. The Japanese Patent Laid-Open No. 11-53093 proposes an input device comprising: a display unit having an input area for displaying a desired key arrangement and a display area for displaying characters and symbols; a data inputting unit for obtaining coordinates data when a key portion displayed in the input area of the display unit is selected; and a key input detection unit and controller for converting the coordinates data corresponding to the key portion selected in the input area into data representing a predetermined character or function, wherein a certain width of boundary areas are defined between the keys displayed in the input area, and if one of the boundary areas is selected, the key to which the boundary area belongs is determined, so that an input assigned to that determined key portion is performed. For example, the boundary areas are set to belong to the respective keys located at the left of them. Then, if a user touches a boundary area, it is determined that the input belongs to the key at the left of the boundary area.
Japanese Patent Laid-Open No. 11-127399 also proposes a method for preventing incorrect inputs in a remote control system that incorporates a touch panel. In this method, a predetermined width of intermediate band is provided among adjacent icons. This intermediate band is the area that does not reflect state transitions caused by selecting the icons. For example, in a remote control system for a video tape recorder, an icon A defines fast-forward while an icon B adjacent to the icon A defines rewind, wherein the intermediate band is provided in between the icons A and B. Here, when a user touches the icon A, fast-forward is selected. Then, if the user moves to the intermediate band to touch the icon B, the selected icon does not change, so that fast-forward remains to be selected.
With the method of the Japanese Patent Laid-Open No. 11-53093, determination that an incorrect input was performed due to a use's selection of a key adjacent to the correct key is made only when the user selects a certain key and then selects a backspace key and the key adjacent to that certain key. That is, determination that an incorrect input was performed requires the user to perform the additional key operation and to input the correct key.
With the method of the Japanese Patent Laid-Open No. 11-127399, if the user in the above example touches the intermediate band while, intending to touch the icon B for rewinding, the intention will not be reflected.
Thus, an object of this invention is to provide an input device that can prevent or reduce incorrect inputs on adjacent keys while reflecting the user's intention as much as possible without the need for additional key operations by the user.